TOKYO — Prime Minister Shinzo Abe secured a crucial victory in Japan’s parliamentary elections on Sunday, with his ruling bloc maintaining a supermajority that could allow it to push for a revision of the nation’s pacifist constitution.

With results still trickling in Monday, public broadcaster NHK reported that Abe’s Liberal Democratic Party and its smaller coalition partner, Komeito, had received at least 312 seats in the 465-seat House of Representatives.

The result further illustrates the political savvy of Abe, 63, who has proved an enduring force in Japanese politics despite scandals and fluctuating approval ratings.

“This is a win for Abe,” said Sheila Smith, a Japan expert at the Council on Foreign Relations, adding that the supermajority showed “a real endorsement of Abe’s leadership”

After a decisive supermajority win for Japanese prime minister Shinzo Abe in the Oct. 22 election, Abe is expected to push for reform of the country’s pacifist constitution. (Reuters)

The decisive victory is expected to bolster Abe’s hopes in an upcoming leadership contest within his party, potentially cementing the prime minister’s place in history. If Abe serves out a complete four-year term, he will remain at the helm during the 2020 Tokyo Olympic Games and become Japan’s longest-serving prime minister.

However, any attempt to amend Japan’s postwar constitution may end up being Abe’s most controversial legacy. With Sunday’s vote, Abe and his allies have retained the two-thirds majorities in both houses of parliament that are required to call for constitutional amendments.

Abe has long sought to revise Article 9, which renounces war, and remove the ambiguity surrounding Japan’s military, known as the Self-Defense ­Forces.

While many conservatives view the amendment as overdue, many voters remain skeptical. South Korea and China, Japan’s neighbors, also are nervous about what they see as the potential return of a militaristic Japan.

In an interview with NHK after polls closed, Abe said he would push for an amendment.

“The ruling parties have been granted a majority,” he said. “I think it was the people’s voice telling us to make progress in politics and bring results with a stable political base.”

For a leader touting stability, the election had been a gamble. Abe had called the vote more than a year early, justifying it by saying that he needed a new mandate to deal with the threat posed by North Korea and to work through the details of a consumption-tax increase.

Many analysts said Abe’s motive was more opportunistic, however, with the prime minister taking advantage of the disarray of the Democratic Party, Japan’s main opposition party, and a small bump in his approval ratings after a number of scandals earlier this year.

For a while, it didn’t look as if the bet would pay off. After the vote was announced, Tokyo Gov. Yuriko Koike, a staunchly conservative former LDP member, founded her own party, which soon attracted many members from the Democrats. Some, including Koike herself, compared her mercurial rise to that of France’s Emmanuel Macron this year.

Unlike Macron, Koike’s challenge did not live up to the hype. The governor opted against running in the election — and then left for a scheduled business trip to France on election day. Koike’s Party of Hope was in third place with 49 seats on Monday morning, as another new party — the anti-amendment Constitutional Democratic Party — placed second with 54.

Speaking to reporters in Paris, Koike said she was disappointed.

“It’s a very harsh result. My remarks and behavior made people feel unpleasant, and that led to the harsh result,” Koike said, according to Kyodo News. “I reflect on this and feel I might have been arrogant.”

In contrast with recent elections in the United States and Europe, relatively few divisive issues were on display in Japan ahead of the vote. This, plus the relative good health of the economy, led Daniel Sneider of Stanford University to call the vote a “Seinfeld election” — an election about nothing.

The LDP has long dominated postwar Japanese politics. For many Japanese voters, Abe’s leadership represents stability after years of short-lived governments before he returned to the prime minister’s office in 2012.

Some analysts suggest, however, that the weakness of the opposition may mask discontent with Abe and a lack of support for many of his policies. One exit poll cited by Kyodo showed 51 percent of voters saying they don’t trust Abe, while 44.1 percent said they do.

Koichi Nakano, a professor of political science at Sophia University, said that the election exposed a lack of widespread support for Abe’s policies. Abe did not win “because people enthusiastically support him,” Nakano said. “People are disaffected and the opposition is divided.”

The bad weather may have also helped Abe. The approaching Typhoon Lan left voters battling strong winds and heavy rain to make it to polling stations. On Monday, Kyodo estimated the final turnout at 53.69 percent, only marginally above a record low in the 2014 election.

That turnout was “remarkable given the weather,” said Tobias Harris, a political analyst with Teneo Intelligence, but it was “ultimately not good enough to give much of a boost to opposition candidates in close races.”

The typhoon delayed final results, with 12 municipalities postponing vote counts until Monday.

Despite the rain, a number of voters could be found exiting a polling station in Tokyo’s cosmopolitan Roppongi neighborhood Sunday morning. Nobue Koizumi, a 67-year-old retired translator, said she had felt compelled to vote because of fears about Abe’s security policies.

“He uses the North Korea issue as his strategy just to win this election,” said Koizumi, who voted for the Constitutional Democratic Party.

But others said they were voting to back the status quo.

“I don’t particularly support Abe, but I do support” the LDP, said Hiroki Shinohara, a 54-year-old wholesaler at the Tsukiji fish market. “I feel it’s doing what’s right for Japan, and Japan needs it.”